With increasing awareness about the environment and in view of depleted oil sources in the future, there has been a need for reduction of fuel consumption in automobiles, motorcycles, etc. Also, secondary batteries such as a lithium ion battery have been making remarkable progresses. Attempts to use electric power as driving power in electric automobiles, hybrid automobiles, etc., have been vigorously made.
In a case where the electric power is used as the driving power for the vehicle, heat generation in the electric motor in which a current of a great magnitude flows or in an inverter (electric power controller) for supplying the electric power to the electric motor becomes problematic. Therefore, it is necessary to efficiently disperse the heat generated in an electromagnetic coil of a stator in the electric motor, a switching element of the inverter, etc., to cool the electric motor, the inverter, etc.
Under the circumstances, conventionally, various structures for liquid-cooling the electric motor and the inverter in the electric vehicles have been proposed. For example, in a cooling structure disclosed in Patent Literature 1, a housing of a motor unit is cooled by a coolant (LLC) in an electric vehicle of a four-wheeled automobile type. The housing is provided with an accommodating section of the electric motor, and an accommodating section for accommodating an inverter and a smoothing capacitor. A module of the inverter and a module of the capacitor which are accommodated in the accommodating section are configured to contact a cooling jacket.
In a motorcycle in which a space for a cooling system is limited, for example, as disclosed in Patent Literature 2, an inverter is air-cooled in many cases. In an electric motorcycle of a scooter type disclosed in Patent Literature 2, a motor controller (electric power controller) is provided under a floor of a battery box accommodating a number of batteries. The motor controller is cooled by traveling wind. In addition, the battery box is provided with an air discharge port which opens toward the motor controller to directly apply discharged air to the motor controller.